We are performing case-control studies within a population-based registry of children with cerebral palsy (CP) born between 1983-1985 in four northern California counties. Work during FY97 included: (a) a study of maternal infection as an important risk factor for CP in infants of normal birthweight, published as the lead article in J.A.M.A. with an accompanying editorial; (b) a paper on potential asphyxiating complications and their association with spastic CP, paper submitted; (c) major new case- control study of CP in very low birthweight infants born in northern California in 1988, with data analysis ready to begin; (d) a study in preparation of transient neonatal hypothyroxinemia in term and near-term infants, finding that low T4 in the first days of life is associated with the risk of CP; (e) publications on determination of gestational age and on what placentas are submitted for pathologic examination; a paper in press on magnesium and neonatal mortality; and papers submitted on potentially asphyxiating conditions and CP, and on the reliability of histologic study of the placental; (f) with Dr. T.M. Phillips of George Washington University, and Dr. J.M. Dambrosia (BFSB), a study of ultramicroassay of blood constituents in newborn infants later recognized to have CP and controls.